I don't know if they made one, but I've seen Graflexes with strap lugs added to them.

If you're looking for a strap for a heavy camera, I like the Calumet Air-Cell strap (RM2004). It distributes the weight nicely but isn't too springy like a lot of the 35mm camera straps out there, so the camera doesn't bounce around excessively. I've been using it on my Technika for a while.